


Hot In Here

by Xanders_collection



Series: Drabbles/One Shots [16]
Category: Ao no Exorcist | Blue Exorcist
Genre: Biting, Blood and Injury, Cannibalism, Come Eating, Demon Sex, Dom/sub Undertones, Feral Behavior, Fluff and Smut, M/M, Master/Servant, Mating Cycles/In Heat, Nesting, Nipple Play, One Shot, Oral Sex, Rough Oral Sex, Scenting
Language: English
Status: Completed
Published: 2020-11-24
Updated: 2020-11-24
Packaged: 2021-03-10 07:55:49
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 4,567
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27700001
Author URL: https://archiveofourown.org/users/Xanders_collection/pseuds/Xanders_collection
Summary: Rin goes into heat, its that simple
Relationships: Amaimon/Mephisto Pheles, Amaimon/Okumura Rin, Amaimon/Okumura Rin/Mephisto Pheles, Belial/Okumura Rin
Series: Drabbles/One Shots [16]
Series URL: https://archiveofourown.org/series/1093761
Kudos: 110





	Hot In Here

**Author's Note:**

> If you're like expecting alot of just smut then I'm here to say unfortunately that's not how this went lmao 
> 
> This is an excuse to write Belial/Rin 
> 
> If you didnt read the tags then a warning for a slight touch of cannibalism

Ever since Rin had pulled the sword from the scabbard for the first time, he noticed that something had changed; other than his new look that consisted of demonic traits, tail, teeth, eyes etc. No this was internal, something was off. He didn’t know what exactly it was but he could feel it. His body was giving him weird sensations.

He had growled the other day and yet has no idea where it came from or why he even did it, Yukio had just laughed. So now with these weird physical feelings came emotions. Not in a conventional sense, no this felt very unnatural to him. It almost felt like it wasn't him, as if it were a deeper part of his being, a more primal part. 

-

Rin shot up when a sharp pain rippled across his entire body, he tensed and a whine escaped him; tears welling up and his distress got much more vocal waking Yukio up in the process. Rin curled in on himself his tail wrapping around his stomach to push pressure. The tight ball position he held was sort of helping. 

“Rin.” A hand touched his shoulder and he uncurled and snapped at the hand that touched, thankfully Yukio was fast enough to pull back. “Rin what the hell?!” Yukio shouted holding his hand to his chest. Rin wiped at his eyes and blinked. “Yukio?” 

“Who else would it be?” 

Rin ran a hand through his hair to fix the bedhead and pulled the blanket back up. “Sorry, don’t know what came over me. Feel weird.” Yukio stared concerned. 

“Are you doing okay? You sounded in pain earlier.” 

Rin shook his head to clear his thoughts, hands clenching the blanket between fists. “Something’s wrong Yukio. Wrong with me.” Yukio just exhaled a laugh and then froze. “Oh, you’re being serious.” Rin turned and snarled; teeth bared with glowing eyes. Yukio stumbled back with a gasp. “Okay, yep yes yeah I get you.” Rin pursed his lips with a hum. 

He inhaled with a shiver, it was hot; he exhaled and felt cold. “Am I sick?” 

-&-

That had happened last week. It just kept getting worse, he had stopped showing up to class after he attacked his brother one of the mornings. He took to staying home and when Yukio would return; he would take off. 

He hopped from the window upon hearing the main door open, Yukio was back. Rin grabbed a pipe and pulled himself up; making his way to the roof seemed better than having to be in the same room as his younger brother. 

“Hey Kuro.” The cat sidhe was relaxing in the sun. “Rin!” 

Rin jumped and rolled up onto the roof. A heavy sigh leaving him. Kuro stretched and approached curling up on his chest. A purr that Rin did not even notice that had come from him had mixed with Kuro’s. “Smell nice.” Rin crossed his arms behind his head and stared at the clouds. “Do I? Must be the shampoo I stole from Yukio.” Kuro nuzzled in. “You presented.”

  
  


“Presented?”

-&-

It came to the time where the two Okumura’s would collect their allowance from Mephisto. The whole walk to his office sucked, Rin felt as if his body weighed tons, he was just so heavy and it took a lot of energy to even move, his tail just dragging along the ground. Yukio knocked before pushing the door open, Mephisto sitting at his desk eating ramen as he always was. 

“Allowance?” Mephisto fished around his pockets for his wallet. Rin groaned and dragged his feet along the floor before he just gave up and fell to the ground pressing his cheek flush to the rug. 

“Oh dear.” Mephisto leaned over his desk and glanced down at the teen. “What’s wrong?” 

Yukio sighed and watched his brother curl up once again. “Something.” He mumbled with a shrug. “Lately he’s just been…this.” He crouched. “And he hisses.” He poked and Rin responded with...of course a hiss.

“Oh, would you look at that.” Mephisto stood and walked around his desk staring at Rin, his foot reaching out to nudge him. “Is this what I think it is?” A smirk on his face. “And what would that be?” Yukio asked knowing he would not get an answer. “Stuff that you shouldn’t bother your pretty little self with.” And there is the answer he knew he would get. “Well can it be dealt with? He’s missing class.” 

“Well now, that’s never good. As your guardian  _ and _ your principal, I will do my utmost best to help!” 

“That doesn’t sound encouraging at all.”

It took no effort on the demon to pick Rin up and throw him over his shoulder. “He needs rest.” Yukio felt his own stomach turn at the sudden shift of space, the three appearing back in their dorm. Rin was dropped haphazardly onto his bed, bouncing with a groan. Mephisto swept the mattress off the bed to the ground dragging Rin around like a ragdoll, summoning blankets to fall atop the glaring teen. 

“Nest, you’ll feel better.” 

“Nest? What are you on about you fricking clown- “Mephisto scoffed and covered Rin’s mouth with a gloved hand. “Youth these days.” He blinked down at Rin who was now trying to bite his hand. “Shall I assist you in giving in?” Yukio stepped forward but stopped when the gaze turned to him. “Sir Pheles- “ 

“Such a bratty little mouth.” His gloved thumb pressing down on his bottom set of teeth to force open his jaw. “Allow me to relax you.” Rin stiffened at the eye contact, the shock of dominance rushing to his core. His eyes narrowed and bright, teeth bared and the growl he let out had Rin melting in place, a whimper falling from his lips. “Nest for me.” 

The tension slipped from his body, ears and eyes drooped with relaxation, a small purr rumbling within his chest. Rin fumbled for blankets, pulling them all around before he would move them repeatedly…and again.

He snapped at Yukio who moved to take a step, flames burning the soles of his shoes. He yelped and kicked them off. 

Rin’s eyes watered and he warbled staring at the blankets, claws ripping them. 

“Oh baby.” Samael cooed cupping the wet cheeks. “Is it not a good place to nest?” Rin sniffled, shaking his head leaning into the touch. 

“What’s- “He shushed Yukio. 

“Let me take care of you.” The trill Rin released gave his answer. “Belial take him. I'll follow along.” 

“Of course, Master.” Yukio jumped and exclaimed a curse. “Jesus fucking Christ where did you come from?!” The servant ignored him to coax Rin into following him. 

“I recommend you avoid Faust Manor for now, Mr Okumura. Rin has been lost to his instincts. This is no longer your busine- “ 

“He is  _ my _ brother!” Yukio gulped the second Mephisto turned and stared. “You forget  _ your _ place.” Taking a step back did not help as Samael just stalked closer. “If you ever interrupt me again, I won’t hesitate to  _ crush _ you. Are we clear, Mr Okumura?” Yukio had never felt such fear, the shaking just would not stop, his mouth not working. “I said,  **are we clear** .” 

“YES!”

“Perfekt! Auf Wiedersehen!” His tone cheerful and calm as if he never even threatened him, body loose and free, the demon had thrown up a peace sign and winked before a cloud of pink and glitter poofed into existence.

-&-

Rin hummed rubbing his face against Belial’s chest, a purr rumbling in his chest. Belial stood awkwardly with his arms hovering at Rin’s sides yet not touching, Samael would have his tail if he dared to try anything after staking a claim…well it wasn’t a permanent one but he could feel it settled within the teen warning him of the danger if he dared touch. He shuffled with Rin to the edge of the bed trying to get him to release him, the Prince’s arms wrapped tightly around him. Rin sat but did not let him go, he blew out a sigh and hesitated at touching the Prince’s hair; yet the purring increased in volume when he settled his hand down and pet. 

Some black appearing in the corner of his vision, a black furred tail tip wagging back and forth in a slow motion. Even instinctually the Prince had no shame about showing his tail. His eyes zoning in on the slow teasing movement, his hand reaching-

“Belial.” He froze. “Whatever do you think you’re doing?” Lord Samael stood staring down at him, eyebrow twitching. He pulled the prince from him pushing Rin behind him and baring his teeth. “Out.” 

Belial bowed and rushed from the room.

Rin peaked out from behind him watching the closed door. “Nest?” He tugged at Mephisto’s cloak. A hand ruffled his hair. “Yes, go nest.” Rin fell back onto the large custom bed that was in Mephisto’s room. Bigger than anything he’s ever seen, and it screamed the perfect place to nest. He shimmed out of clothes, rolled, and squirmed spreading his scent all over the blanket and pillows. His tail wagging at a perfectly scented pillow. He kneaded it and pushed it to the side setting up a circle with the pillows. He pushed his shirt off to the side filling in a gap, his trousers thrown off the side of the bed with a grunt. Mephisto dodged the shoes and socks thrown his way, Rin now rolling around in his underwear nuzzling his face into his pillow. Rin shot up with a whine. Something was missing. 

Rin crawled on all fours towards the other demon, hand reaching out towards him and clutching his cloak and with a hard yank it came loose and Rin stole it, he spread it out under him and lay on top with a content purr. 

Rin exhaled a breath of blue flame and covered his face with Samael’s pillow inhaling loudly. 

Samael matched his purr and watched his head pop out and stare until the face broke out into a smile. “Nest…Come?” Rin grinned, rolling onto his belly grabbing Samael’s hand and pulling him in. The teen giggled and forced him to lie down and immediately crawled on him rubbing his cheek to his chest. “Smell nice.” Samael hummed and wrapped his hands around him. “You smell nice too.” Rin wiggled and licked up his neck trilling at the exhale. He was scenting him. 

It did not take long for Rin to roll over and fall asleep, it was his chance to get up and leave without disturbing him. 

Outside the door stood Belial. “Attend to him if he needs anything. I’ll be in my office.” His servant nodded and watched him walk off. “Oh, and Belial? Don’t touch.” 

-&-

Mephisto stared wistfully at the door that was slammed, his cheek a bright red. “What a woman.” Shura had paid him a visit after hearing what he had said to Yukio, she had not hesitated to slap him across the face.

“My older brother has such weird tastes.” Mephisto directed his gaze to the floor to see a green hamster crawling up his leg and dropping onto his lap only to poof to a human form. Amaimon leaned over and picked up a sweet from the bowl on his desk. Mephisto’s horn twitched. “Amaimon.” His voice was bitter. 

“Huh? What is it?” The earth king shifted in his lap to face him, gold eyes blinking until his head tilted. “Smell. What’s that smell?” Amaimon’s hands pulled at his collar and inhaled. Mephisto watching Amaimon’s eyes dilate. “Heat.” A slick tongue licking up his neck just as Rin had done. “I smell a demon in heat.” 

“Good nose, now can you get off?” 

“It’s not Belial…who? Who is it Samael?” Amaimon bit back and shook his older brother by the tie. “There are no other demons, Amaimon. Think. Who else could it be?” Mephisto tightened his tie when the younger stopped and stared off into nothingness, pupils contracting. “ _ Okumura _ .” He hissed, tongue out tasting the scent in the air. 

-&-

Rin pulled a pillow between his legs and whined, grinding against it. He ached and burned with arousal. Hips rolling into the delicious friction. 

Belial stood staring with a tray of food, it almost slipped from his hands at the moan, the prince rolling onto his back showing his belly watching with hooded eyes. Rin’s eyes tracked him as he walked to the nightstand and placed the food down. “You must eat, my Prince.” He didn’t dare sit; Rin was watching too intensely. Teasing him to enter. 

He inhaled sharply when the Prince stuck his hands under his underwear. He turned to pick up an orange and sliced it. “You must be hungry. Eat.” 

Rin sat up removing his hands and licked his fingers before crawling over. He sat and opened his mouth. “Feed.” Belial didn’t know if he would survive. How could he not touch what was asking to be touched. The Prince wanted him. He placed an orange slice on the awaiting tongue and swallowed. Samael was going to destroy his being after mauling his body. 

With each slice Rin got more antsy, his thighs rubbing at his erection. The final slice had him wrapping his lips around Belial’s fingers and licking them. 

“Oh Gehenna.” Belial mumbled at the scene; he could smell the Prince’s want. Rin grasped his wrist and licked at each finger. “Off.” He muttered, wiggling his hips. The servant placed his other hand on the waistband of Rin’s boxers and pulled them down, the teen raising his hips while still sucking on his fingers. 

Samael is going to enjoy punishing him. 

Rin directed his now wet hand down to his cock, his two hands holding him up and he spread his legs. 

Belial cursed Satan for making such a minx of a demon. How could he say no to this beautiful desperate display? His prince panting with a blush adorning his face, chest pushed out by the angle he was leaning at. Belial could not stop himself even if he tried. He pressed a kiss to the arched chest and couldn’t help but wrap his lips around a perky pink nipple, his hand closing around the Prince’s cock. Rin exhaled a moan letting his head fall back and bucked up into Belial’s hand. Samael be damned, Belial was going to enjoy what the Prince offered. 

“Ha…” Rin gasped and dropped to wrap his hands in Belial’s hair, sharp teeth nibbling at his nipple. “More.” He hummed and kissed down to stop at the curls of hair, leaning up to press a kiss to the glistening head of his cock. “Please.” The Prince begged so prettily. He sucked and tongued at the cock in his mouth, sudden thrusts pressing it further in. He watched the prince grab at the blankets and whine, his knuckles white at how tightly he pulled. The noise Rin made when he took him into his throat made him moan. A hand gripped his hair and pulled. He licked up the base until he popped off. The Prince staring with glowing blue eyes. 

“Do you want to fuck my mouth, my Prince?” Rin whined and dropped his head back down. He would take that as a yes. Hands softly gripped his hair and pulled him back over his cock, Belial opening his mouth happy to be used. Rin was rough and desperate, chasing a pleasure he had never felt before. His head was pulled up and with the sound of a choked moan the prince had cum all over his face. 

The prince panted and nudged at his face when he sucked the tip of his cock whining at the over stimulation. Rin pushed himself up and grabbed Belial’s face staring blankly. He leaned in and licked up his own cum. How could such an oblivious demon be this forward. To think that the prince didn’t even know what he was doing to him. 

-&-

  
  


Amaimon threw open the doors with Belial following behind chattering about how he was not allowed in. 

There sitting on the bed sat Rin Okumura with bed head and eyes glazed over. The room smelled of sex. “You? And him?” Amaimon barked out a laugh. “He must have been desperate. Get out.” 

“My Lor- “ 

Amaimon bared his teeth. “Out!” The servant left with a bow. Amaimon spun and strolled towards Rin. 

“Pretty nest.” He commented and placed his hand on the bed getting ready to climb on until he screamed jumping back clutching his burned hand to his chest. Rin had burned to his bone. It didn’t hurt as much but the surprise of it shocked him more. He growled baring his teeth only to have it mirrored back at him. Amaimon paced back and forth bemused, it had been awhile since someone met his challenge. 

“You let him in and not me?!” He growled narrowing his eyes and he pounced only to be thrown out. He snapped his teeth at the teenager and stood back up. “I am King Of Earth!” He clenched his fists. “He is but a servant!” 

Rin watched him on all fours, tail high and waving slowly with teeth bared. He was snarling at him. He took a step forward and this time Rin pounced, his teeth biting in deep into his forearm drawing blood. He shrieked when blue flames erupted around them, burning him rapidly. If Rin didn’t release, his host would be decimated so he did the one thing he knew would make it easy to escape. He dropped to the ground falling flat and exhaled a sigh, his four legs giving up. The hamster form was always helpful. 

Rin retreated to his nest and curled up, he refused to look away and take his eyes off the green ball of fur lying flat. 

Amaimon reverted and stretched his arms up with a loud yawn, he blinked tiredly with a sigh. Usually demons ranked below him let him in their nests without being asked, even his brothers let him into their nests. Amaimon sighed heavily. He had to appeal and prove himself worthy.

“Your nest is so pretty.” Rin glowed at the praise, tail wagging. “Let me provide for you.” He cooed and let his aspect stretch out, Rin mewled. This time when Amaimon reached in Rin just purred leaning his cheek into the earth king's palm. “How beautiful.” He sniffed and crawled up. “Smell so nice.” Rin’s purrs were content and relaxed. With another demon rubbing all over him to spread his scent had his nerves alight. “Pretty little demon.” 

Amaimon wrapped his arms around him and pressed his face into the dark curls and listened to the younger’s breath even out until it slowed and the body in his grasp fell limb, Rin had dozed off. 

It was a tad odd that Rin wasn’t making lustful advances, heat usually makes one insatiable, yet here he lay napping on his chest and drooling on his shirt. Even Nephilim experienced it so why was Rin so calm, other than the quick release with Belial he had done nothing sexual and that wouldn’t even be enough, the servant was below them. The ones who could satisfy Rin are any of the Baal. 

He pondered while petting his younger brother. 

To drop Rin in front of Lucifer in this state would be interesting. It is an unspoken agreement that the war would be null if one showed up due to heat. Samael and Lucifer often pausing their quarrels to rut and roll around in bed together. Although, he had to admit how hilarious it was to see Lucifer flushed standing at the door. Once they fought so much that they both triggered their heats and to watch them send away their allies was a joy. To be as they were before everything went to shit. He sighed heavily. He missed his brothers. The last time everyone was together was the Blue Night incident.

-&-

“Come on, you should be begging me to fuck you.” Amaimon said, staring at Rin who was wrapped in Mephisto’s blanket sitting at an island in the kitchen, Rin just shoved ice cream in his mouth and Amaimon groaned, throwing his hands up. 

“More, my prince?” Belial held up a tub.

Rin smiled with shut eyes and dumped a whole container of sprinkles into the bowl. “Okay yeah screw this.” Amaimon tugged a stool out, Rin cringing at the shriek it made. He slumped next to him and grabbed a spoon digging into the cold desert along with Rin. 

“Bleh.” He stuck his tongue out at the brain freeze.

Rin chirped next to him and Amaimon nearly fell from the chair at how aggressively the other had crawled into his lap, not to mention how fast he had sucked his tongue into his mouth. “Mmffh-“ 

Hands gripped his horn yanking him down lower, it was so sweet, cold, and warm and…and hot. Now this is what he’s been waiting for.

  
  
  


-&-

  
  


Mephisto wiped his hand with his own brand of tissue, blood staining the soft white. This job was a nuisance. During a meeting he had clenched his fists too tight and drew blood. 

It had been a couple hours since he had left Rin, Amaimon had probably found the boy by now. It would be a surprise if he hadn’t. At least he could return home for now--A knock on his door. 

“Sir Pheles?”

Yukio. He huffed and dropped back into his chair. “Yes, Mr Okumura?”

Yukio approached the desk and nudged his glass up. “Uh, about Rin-“ 

“I thought I told you that it was none of your business?” Mephisto said with droopy eyes, he could go for a nap right now. “I did, didn’t I?” Yukio nodded, “You did, you uh, also threatened me.” 

“Fun times. Anyway, what do you want?” Mephisto was dying for a nap, an hour or two would be perfect especially with Rin. The boy was like a heated blanket, so warm and soft. He bet the nest smelled even more like him. 

"To see him?" 

  
  


No no no, that wouldn't do, Rin would just feel threatened and snap at him. He made it clear the first time that Yukio wasn't a suitable mate, he doubted he'd let his brother trespass on his nest.

'Wait, that would be entertaining.' 

"He's not in the right mindset right now." Mephisto commented and let out a yawn. Yukio sighed letting his shoulders drop. "I still want to see him." He wouldn't give up. "Fine, but if he attacks you it's not my fault." 

"Attacks me?!" 

-&-

Yukio followed close behind Mephisto, the two walking down a long hallway. 

He pushed open the doors and within lay Rin, Amaimon and Belial. 

Belial was standing next to the bed brushing Rin's hair, the teen steadily purring, Amaimon had his head in lap playing a video game from one of his many consoles. 

Rin slowly glanced over and his purr abruptly fell, his eyes locked to the human standing right next to him. 

Mephisto approached the bed and jumped onto it, a cloud of pink replacing his clothing with pyjamas. He snuggled under his blankets and pulled his eye mask down. 

Yukio took just a step forward and growling picked up, Rin now glaring at him with his teeth bared. "I wouldn't recommend another step, Okumura." Mephisto warned and peaked out from under her mask not wanting to miss the many possibilities he has already foreseen. 

"Rin-" He took another and spotted his brother's tail stick high into the air; the fur along it spiking up. This time his brother snapped his teeth at him and the sound of teeth cracking off each other was loud enough to make him falter in his steps. 

"Mr Okumura, you understand how demons behave from your studies, don't you? Then do tell me, why are you approaching a hostile and feral one?" 

Yukio paused unsure of how to answer, he didn't know why. 

"Rin-" His hand reached out and it burned with white hot pain, Rin's teeth deeply embedded and he silently screamed in pain. He was forced back by a green blur- Amaimon standing in front of him while he cried out holding his bleeding hand to his chest. 

"You  _ idiot!" _ Amaimon snarled at him without turning, his eyes trained to Rin who licked at his blood stained teeth. "You never let a feral demon taste blood!" Blue eyes locked to him and tackled only to get a forearm shoved in his mouth. 

Amaimon hissed at the sharp pain of Rin's teeth biting into him, his jaw clenching and ripping his flesh from his bone. Yukio froze. He was unable to move watching his brother chew and swallow. "Get  _ out!"  _

His feet stumbled and he slipped before finally gaining traction and slamming the doors behind him, Rin banging into them with a growl; Amaimon's hands gripping Rin by the tail to hold him back. 

"Come here!" He spun him away from the door and was pinned, his shoulder burning at the teeth forcing themselves in and biting to the bone--An audible snap and yell at the shattering of bone followed by crunching of teeth. 

"Belial." Mephisto reached for his servant and slowly encouraged him to hide behind him after he slipped out of the bed. He slipped a key into his hand. "Do leave if you find an opportunity." 

  
  


Rin's claws harshly dug into Amaimon's chest and he snapped his teeth at him, the earth king's head falling back down to hit the tile. 

"Samael," He rasped. "He's forcing my heart out." Amaimon with his free hand grasped Rin's face and squeezed only to have to hand bit. The bud of his heart appeared suddenly and he screeched at teeth biting into one of the spread leaves; Samael gripped Rin by the hair and yanked his head back, Rin whining. 

" **Enough.** " 

The whine transitioned to a giggle and he smiled. "Play." 

Samael shook his head. "No Rin, you can't play." Amaimon groaned and clutched his chest, his heart disappearing. "My aspect hurts." Samael picked Rin up off him and sat him on the bed. "Yes I would imagine so. He did just bite it with his own." 

He sighed and kneeled in front of Rin. "I think we may have to spend this cycle in Gehenna." Amaimon shot up. "But Father-" 

"Will not disturb us. Even he will sense how unstable he is." He gestured to Amaimon's wounds. "You still haven't healed. It's not safe here." He turned his attention back to Rin who was kicking his legs. "We may have to call Lucifer to help with this." 

"Maybe not." Amaimon cringed at his blurred vision, the blood loss getting to him. "He tried to claim me, it was violent." He blinked the blurriness away and watched his forearm slowly knit itself together. "He shoved his aspect in. I don't think he's aware that he was doing so." 

"Well that will be a problem. If he claims Lucifer is what I mean." He rolled his eyes and huffed. "Fine, Yes, Amaimon you can claim him or let him claim you--Did you just finger gun at me?" He face palmed. "Stop hanging out with humans. Its ruining how much I can tolerate you."

He grinned. "No." 


End file.
